Wal-Mart data sources

All of the data on my blog comes from public data sources.
The primary source of this public data is Wal-Mart's filings with the SEC.

Wal-Mart's CIK number with the SEC is 104169.
The CIK number is the Central Index Key and it is the number that the SEC uses to identify all filings related to Wal-Mart.

The link below will take anyone to all of the most recent Wal-Mart filings at the SEC.

http://www.sec.gov/cgi-bin/browse-edgar?CIK=0000104169&action=getcompany

Form 10-K = annual financial statements
Form 10-Q = quarterly financial statements
Form Def 14A = the proxy statement

You can get almost everything from those three types of forms.
For some additional information, you can consult the company's official annual report, which is available here.